Calculating pi with BigDecimal - problem

Hello,

I have a problem with my program that I've written:
I try to calculate pi as exact as possible with Leibniz' algorithm:

(pi/4)=(1/1)-(1/3)+(1/5)-(1/7)+(1/9).... etc.
Quickly I discovered I would need exacter numbers so I decided to use BigDecimal.
However when calculating the next term (e.g. -1/3 or 1/5) it does not calculate it correctly.

This is my new code but it gives the following error:
" at Leibniz.main(Leibniz.java:25)
java.lang.ArithmeticException: Non-terminating decimal expansion; no exact representable decimal result.
at java.math.BigDecimal.divide(BigDecimal.java:1603)
at Leibniz.main(Leibniz.java:30)
"

I replaced all the int's with BigDecimals so I could divide, multiply etc....